JP2990233B2 - Liquid crystal electro-optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-optical device using a nematic liquid crystal which uses a thin film transistor and has excellent characteristics of high-speed response, high contrast, and steep response to an applied voltage.

[0002]

2. Description of the Related Art Conventionally, a TN (Twisted Nematic) type liquid crystal electro-optical device has been used as a display element of a timepiece, a calculator or the like. The configuration of the TN liquid crystal electro-optical device will be briefly described.

By injecting nematic liquid crystal having a positive dielectric anisotropy between substrates which are aligned at an angle of 90 ° to each other, twist alignment of liquid crystal molecules occurs. When an electric field is applied to the liquid crystal, the major axis of the liquid crystal molecules is oriented perpendicular to the substrate due to the interaction between the electric field and the dielectric anisotropy. The state (twist) of the liquid crystal molecules when no voltage is applied to the liquid crystal and the state when the voltage is applied are distinguished by using a polarizing plate. Alternatively, conversely, there is a method in which a nematic liquid crystal having a negative dielectric anisotropy is interposed between one of the substrates subjected to the vertical alignment processing.

In recent years, research on ferroelectric liquid crystals has been very advanced. The structure of an optical device using ferroelectric liquid crystal is about 2 μm, which is much smaller than that of a TN type liquid crystal device. I do. The ferroelectric liquid crystal molecules have two stable states without applying an electric field, and the molecules are oriented to one stable state by applying an electric field. By applying an electric field in the opposite direction, the molecules are oriented to another stable state. By distinguishing the state of the two liquid crystals using a polarizing plate, light and dark were displayed.

[0005] In the case of an optical device using this ferroelectric liquid crystal, the response time is very fast, approximately several tens of microseconds, and therefore, applications to various fields have been expected.

[0006] Alternatively, there is an active type in which switching elements such as TFTs and MIMs are arranged in each pixel.

Further, there is an STN type liquid crystal in which a twist angle of a nematic liquid crystal is set to 180 ° to 270 °.

[0008]

However, the above-mentioned T
In an N-type liquid crystal electro-optical device, a liquid crystal alignment film must be formed on both a pair of substrates, and a rubbing process must be performed on the alignment films on the pair of substrates so that they are at 90 ° to each other. Did not. Further, the TN type liquid crystal electro-optical device has a very slow response time of several tens of milliseconds and has a poor response to an applied voltage, so that its application range other than a small area display such as a clock or a calculator is limited. Was. In order to further increase the response speed, a method of shortening the substrate interval is conceivable.However, if the substrate interval is shortened, the liquid crystal can be twisted at 90 ° between one substrate and the other substrate. Disappears.

Although the response time of an electro-optical device using a ferroelectric liquid crystal is certainly fast, there are many problems.

The first problem is that it is very difficult to control the alignment of the liquid crystal. Conventionally, in addition to rubbing, oblique evaporation of silicon oxide, a method of applying a magnetic field, and a temperature gradient method have been performed, but no uniform alignment can be obtained at present under any of the methods. Therefore, high contrast cannot be obtained.

Second, a liquid crystal exhibiting a smectic phase can be used as a ferroelectric liquid crystal. Therefore, the ferroelectric liquid crystal has a layer structure peculiar to the smectic liquid crystal. Once this layer structure is broken by an external force, it does not return even if the external force is removed. In order to restore this, it is necessary to heat and once make a phase transition to an isotropic phase, so that a ferroelectric liquid crystal having a layered structure that collapses due to a small external impact is not practical.

Third, the ferroelectric liquid crystal accumulates charges at the interface with the alignment film due to the spontaneous polarization of the liquid crystal itself, and forms an electric field in the direction opposite to the polarization of the liquid crystal. If you display it, the next time you try to display a different screen,
There is a problem that the previous display remains (referred to as "burn").

Fourth, the contrast ratio of an electro-optical device using a ferroelectric liquid crystal greatly depends on the tilt angle (or cone angle) of the liquid crystal. The value is 22.5 ° (45 °)
It is known that However, liquid crystals satisfying only the condition that the tilt angle (cone angle) is 22.5 ° (45 °) have already been synthesized, but other important conditions, such as the problem of the temperature range in which the liquid crystal exhibits ferroelectricity, Ferroelectric liquid crystals that can sufficiently satisfy the problem of responsiveness to an AC pulse and the like have not yet been developed. Therefore, at present, the problem of the temperature range is more important than the tilt angle. Therefore, the contrast ratio of an electro-optical device using a ferroelectric liquid crystal which is currently under study is not very large. At present, it is very difficult to apply a ferroelectric liquid crystal as a display device due to the problems described above.

[0014]

According to the present invention, there is provided a liquid crystal electro-optical device in which a nematic liquid crystal having a positive dielectric anisotropy is interposed between a pair of substrates. A surface of one of the substrates in contact with the liquid crystal has a liquid crystal alignment layer on which an organic substance is rubbed, and one of the pair of substrates has a channel length longer than a length of the gate electrode in a channel direction. The TFT is provided as a liquid crystal switching element.

In the present invention, the liquid crystal alignment layer may have a liquid crystal alignment film formed on a surface of the pair of substrates in contact with both liquid crystals, in which case the rubbing treatment may be performed on only one of the substrates. It may be applied to both substrates. However, when applied to both substrates, the directions should be substantially parallel. Here, “parallel” means that the rubbing directions of the substrates are 0 ° or 180 ° (anti-parallel).

The liquid crystal used in the present invention may be a cholesteric (chiral nematic) liquid crystal, but a nematic liquid crystal is more preferable. In the present invention, the conventional T
While the distance between the substrates of the N-type liquid crystal electro-optical device is about 8 μm, the present invention generally does not exceed 5 μm, preferably 3.5 μm
m or less, the rubbing effect can be exerted on the entire liquid crystal even when only one substrate is subjected to the rubbing treatment, and the liquid crystal molecules can be aligned in a substantially rubbing direction in the entire liquid crystal layer. .

In the present invention, the liquid crystal is set to 90
Since twist orientation of ° is not generated, it is not possible to perform display using the conventional light-emitting property. Therefore,
In the present invention, display is performed utilizing the refractive index anisotropy of the liquid crystal. The gate electrode used in the present invention can be mainly made of titanium (Ti), aluminum (Al), tantalum (Ta), chromium (Cr) alone or an alloy thereof.

FIG. 1 shows a basic configuration (one example) of a TFT that can be used in the present invention. A blocking layer 24 is provided on an insulating substrate 25, and a source region 20, a drain region 21, and a channel region 19 are formed thereon as semiconductor layers.
Is provided. On the channel region 19, a gate insulating film 17 and a gate electrode 15 on which an oxide layer 16 as an insulating layer is formed by anodizing a material capable of being anodized are formed. A source electrode 22 and a drain electrode 23 are provided in contact with the source region and the drain region, respectively.

As shown in FIG. 1, a material capable of anodic oxidation is selected for the gate electrode portion to be the gate electrode 15 and the oxide layer 16, and the surface portion thereof is anodized to form the oxide layer 16. Source region 20 for ion implantation
Distance between the drain region 21 and the channel length 28
Is approximately twice as long as the thickness of the oxide layer 16 than the substantial length of the gate electrode 15 in the channel length direction. The material of the gate electrode portion is mainly titanium (Ti), aluminum (Al), tantalum (Ta), chromium (C
r), silicon (Si) alone, or an alloy thereof is suitable.

As a result, in the portions 26 and 27 in the channel region 19 which face the oxide layer 16 formed on both side surfaces of the gate electrode via the gate insulating film 17, no electric field is applied by the gate electrode or the gate electrode has no electric field. Very weak compared to the vertically lower part.

This TFT is manufactured by forming a semiconductor layer serving as a source, a drain, a channel region and a gate insulating film layer 17 and then forming a gate electrode portion with an anodic oxidizable material. Alternatively, the source region 20 and the drain region 21 are formed by implanting impurity ions to be made n-type, and then the surface of the gate electrode portion is anodized to form the gate electrode 15 and the oxide layer 16 and subjected to a heat treatment step or the like. That is.

Alternatively, after the semiconductor layer and the gate insulating film layer 17 are formed, a gate electrode portion is formed using an anodic oxidizable material, and then the surface of the gate electrode portion is anodized to form the gate electrode 15 and the oxide layer 16. After forming, the source region 20 and the drain region 21 may be formed by implanting impurity ions for making the semiconductor layer into p-type or n-type, and then performing a heat treatment process.

By performing the above-described steps, an insulated gate field effect transistor having a channel length longer than the length of the gate electrode in the channel length direction can be easily and reliably formed without causing a variation in performance due to a mask shift or the like. Can be manufactured.

[0024]

In the present invention, nematic liquid crystal having a positive dielectric anisotropy is used, so that it is very easy to control the alignment of the liquid crystal. Since a layer is not formed unlike a smectic liquid crystal, the alignment is once disturbed by an external force. After the removal of the external force, the orientation quickly returns to its original state, so that there is no need to heat to an isotropic phase or a nematic phase.

Further, although the nematic liquid crystal is used, the alignment layer may be formed on only one of the substrates or on both of the substrates. If both are formed, the rubbing treatment may be performed on only one substrate, or the treatment may be performed on both substrates in parallel.

When the alignment layer is formed on only one substrate, the number of steps can be reduced as compared with the conventional case. When the alignment layer is formed on both substrates, ITO having generally severe unevenness can be obtained.
When the alignment layer is formed on both substrates and the rubbing treatment is performed in parallel, the alignment regulating force of the substrate with respect to the liquid crystal molecules becomes strong, so that the adverse effect on the alignment of the liquid crystal on the surface of the transparent electrode can be removed. The response time (called fall time) of the liquid crystal when the state where the long axis of the liquid crystal molecules is perpendicular to the substrate by applying an electric field to the liquid crystal changes to a state where the electric field is removed can be shortened.

In the case where the nematic liquid crystal is oriented without being twisted, a considerably large voltage (10 V or more) is normally required to drive the nematic liquid crystal. With the use of a TFT having a high voltage, a large voltage can be applied.

Further, according to the present invention, in a conventional TFT having an activated channel portion made of polycrystal or the like, the point where the OFF current (drain current when the gate electrode is OFF) becomes large, the channel length is reduced by the gate length. This is covered by using a TFT longer than the length of the electrode in the channel length direction, the OFF current is reduced, and the voltage holding ratio of the element is increased, thereby enabling clear display.

In addition, in each case of the present invention, the response time of the liquid crystal is much faster than that of the conventional TN type liquid crystal, and the rise time when an electric field is applied is approximately several tens of microseconds. This value approximately corresponds to the response time of the ferroelectric liquid crystal. In addition, since a TFT element is used in the present invention, a large-screen display can be performed regardless of whether or not the voltage-transmission curve of the liquid crystal is steep. Examples will be described below.

[0030]

【Example】

[Embodiment 1] In this embodiment, a viewfinder for a video camera using a liquid crystal electro-optical device having a diagonal of 1 inch is manufactured, and the present invention is implemented. In this embodiment, the number of pixels is set to 387 × 128, and the high mobility TFT by the low temperature process having the structure of the present invention is used.
An element using the (thin film transistor) was formed to form a viewfinder. FIG. 3 shows an arrangement of active elements on a substrate of a liquid crystal display device used in this embodiment, and FIG. 2 shows a circuit diagram of this embodiment. FIG. 4 illustrates a manufacturing process showing the AA ′ cross section and the BB ′ cross section of FIG. AA 'section shows NTFT, and BB' section shows PFT.
3 shows a TFT.

In FIG. 4A, an inexpensive glass substrate 5 that can withstand heat treatment at 700 ° C. or less, for example, about 600 ° C.
A silicon oxide film as a blocking layer 52 is formed on the substrate 1 by using a magnetron RF (high frequency) sputtering method.
It is manufactured to a thickness of 000 mm. Process condition is oxygen 100
% Atmosphere, film formation temperature 150 ° C, output 400-800W,
The pressure was 0.5 Pa. The film formation rate using quartz or single crystal silicon as a target was 30 to 100 ° / min.

A silicon film was formed thereon by LPCVD (low pressure gas phase), sputtering or plasma CVD. When formed by the reduced pressure gas phase method, the temperature is 1
450-550 ° C lower by 00-200 ° C, for example 530 ° C
CVD of disilane (Si ₂ H ₆ ) or trisilane (Si ₃ H ₈ )
The film was supplied to the apparatus to form a film. Reactor pressure is 30 ~ 300
Pa. The deposition rate was 50-250 ° / min.
Threshold voltage (Vt) between PTFT and NTFT
In order to control substantially the same as in h), boron may be added at a concentration of 1 × 10 ¹⁵ to 1 × 10 ¹⁸ cm ⁻³ during film formation using diborane.

When the sputtering method is used, the back pressure before the sputtering is set to 1 × 10 ⁻⁵ Pa or less, and single crystal silicon is used as a target in an atmosphere in which hydrogen is mixed with 20 to 80% of argon. For example, argon was 20% and hydrogen was 80%.
The film formation temperature was 150 ° C., the frequency was 13.56 MHz, the sputter output was 400 to 800 W, and the pressure was 0.5 Pa.

When a silicon film is formed by the plasma CVD method, the temperature is, for example, 300 ° C., and monosilane (SiH ₄ ) or disilane (Si ₂ H ₆ ) is used. These were introduced into a PCVD apparatus, and a high-frequency power of 13.56 MHz was applied to form a film. The coating formed by these methods preferably has an oxygen concentration of 5 × 10 ²¹ cm ⁻³ or less. If the oxygen concentration is high, it is difficult to crystallize, and the heat annealing temperature must be increased or the heat annealing time must be increased. If the amount is too small, the leakage current in the off state increases due to the backlight. Therefore, 4 × 10 ¹⁹ to 4 × 10 ²¹ cm ^-3
Range. Hydrogen is 4 × 10 ²⁰ cm ^-3 and silicon 4 × 10
It was 1 atomic% when compared with ²² cm ^-3 .

After forming an amorphous silicon film to a thickness of 500 to 5000 °, for example, 1500 ° by the above method, heat treatment is performed at a temperature of 450 to 700 ° C. for 12 to 70 hours in a non-oxide atmosphere at a medium temperature. For example, it was kept at a temperature of 600 ° C. in a hydrogen atmosphere. Since a silicon oxide film having an amorphous structure is formed on the surface of the substrate under the silicon film, no specific nucleus is present in this heat treatment, and the whole is annealed uniformly. That is, it has an amorphous structure at the time of film formation, and hydrogen is simply mixed therein.

By the annealing, the silicon film shifts from an amorphous structure to a highly ordered state, and a part of the silicon film exhibits a crystalline state. In particular, a region having a relatively high order in a state after the formation of silicon is particularly likely to be crystallized to be in a crystalline state. However, since the silicon existing between these regions is bonded to each other, silicon mutually pulls each other. When measured by laser Raman spectroscopy, a single crystal silicon peak 522 is obtained.
A peak shifted to a lower frequency side than cm ⁻¹ is observed. Its apparent particle size is 50 to 5 when calculated from the half width.
Although it is a microcrystal with a size of 00Å, there are actually a large number of regions with high crystallinity and a cluster structure, and a semi-amorphous structure film in which each cluster is bonded to each other by silicon (anchoring). Could be formed.

As a result, the coating exhibits a state substantially free of grain boundaries (hereinafter referred to as GB). Carriers can easily move from one cluster to another through anchored locations, resulting in higher carrier mobility than so-called GB polycrystalline silicon. That is, hole mobility (μh) = 10 to ²⁰⁰ cm ² /
VSec, electron mobility (μe) = 15 to 300 cm ² / V
Sec is obtained. On the other hand, the coating may be polycrystallized by a high-temperature annealing at 900 to 1200 ° C. instead of the annealing at the medium temperature as described above, but in that case, segregation of impurities in the coating by solid phase growth from nuclei. In addition, impurities such as oxygen, carbon, and nitrogen are increased in GB, and the mobility in the crystal is large. However, a barrier is formed in GB to hinder the movement of carriers there. 10cm as a result
^The reality is that it is difficult to obtain a mobility of ² / Vsec or more. For this purpose, the concentration of impurities such as oxygen, carbon, nitrogen, etc., needs to be reduced from several tenths to several tenths than semi-amorphous ones. If you do so, 50-100 cm ² /
Vsec was obtained.

The silicon film formed as described above was subjected to photoetching to produce a semiconductor layer 53 for NTFT (channel width 20 μm) and a semiconductor layer 54 for PTFT. On this, a silicon oxide film to be a gate insulating film is 500 to 200
It was formed to a thickness of 0 °, for example, 1000 °. This was made under the same conditions as those for forming the silicon oxide film as the blocking layer.
A small amount of fluorine may be added during film formation to fix sodium ions.

Thereafter, an aluminum film was formed on the upper side. This was patterned using a photomask, and FIG.
(B) was obtained. A gate insulating film 55 for NTFT and a gate electrode portion 56 are formed.
0 μm, that is, the channel length was 10 μm. Similarly,
A gate insulating film 57 for the PTFT and a gate electrode portion 58 were formed, and the length in the channel length direction was 7 μm, that is, the channel length was 7 μm. Also, both gate electrode portions 5
The thickness of both 6, 58 was 0.8 μm. In FIG. 4C, boron (B) was added to the PTFT source 59 and the drain 60 at a dose of 1 to 5 × 10 ¹⁵ cm ⁻² by ion implantation. Next, as shown in FIG. 4D, a photoresist 61 was formed using a photomask. N
Phosphorus (P) as TFT source 62 and drain 63
Was added by an ion implantation method at a dose of 1 to 5 × 10 ¹⁵ cm ⁻² .

Thereafter, the gate electrode was anodized. L-tartaric acid was diluted in ethylene glycol at a concentration of 5%, and the pH was adjusted to 7.0 ± 0.2 with ammonia. The substrate was immersed in the solution, the positive side of the constant current source was connected, the platinum electrode was connected to the negative side, a voltage was applied at a constant current of 20 mA, and the oxidation was continued until the voltage reached 150V. Further, 0.1 mA is applied at a constant voltage at 150 V.
The oxidation was continued until: In this manner, a barrier type anodic oxide is formed on the surfaces of the gate electrode portions 56 and 58.
An aluminum oxide layer 64 was formed to obtain a gate electrode 65 for NTFT and a gate electrode 66 for PTFT. The aluminum oxide layer 64 was formed to a thickness of 0.3 μm.

Next, annealing was performed again at 600 ° C. for 10 to 50 hours. The source 62 and the drain 63 of the NTFT and the source 59 and the drain 60 of the PTFT were formed as N ⁺ and P ⁺ by activating impurities. Channel formation regions 67 and 68 are formed below the gate insulating films 55 and 57 as semi-amorphous semiconductors. This TFT
In the fabrication, the order of ion implantation of impurities and anodic oxidation around the gate electrode may be reversed.

As described above, by forming the insulating layer made of metal oxide around the gate electrode, the substantial length of the gate electrode is twice the thickness of the insulating film rather than the channel length. In this case, the leakage current at the time of reverse bias could be reduced by providing an offset region where an electric field was not applied. In this embodiment, the thermal annealing was performed twice in FIGS. 4A and 4E. But Figure 4
The annealing in FIG. 4A may be omitted depending on the desired characteristics, and both may be replaced by the annealing in FIG. 4E to shorten the manufacturing time. In FIG. 4E, a silicon oxide film was formed on the interlayer insulator 69 by the above-described sputtering method. This silicon oxide film may be formed by an LPCVD method, a photo CVD method, or a normal pressure CVD method. 0.2 to 0.6 for interlayer insulation
The thickness was formed to be, for example, 0.3 μm, and then a window 70 for an electrode was formed using a photomask. further,
As shown in FIG. 4F, aluminum is formed on the entire surface by sputtering, and leads 71 and 73 and contacts 72 are formed using a photomask. A resin was applied and formed, and the electrode drilling was performed again using a photomask.

An ITO (indium tin oxide film) was formed by a sputtering method in order to make the two TFTs complementary and to connect the output terminals thereof to the electrode of one pixel of the liquid crystal device as a transparent electrode. This was etched using a photomask to form an electrode 75. This ITO
Was formed at room temperature to 150 ° C. and achieved by oxygen at 200 to 400 ° C. or annealed in the air. Thus, NTFT 76, PTFT 77 and transparent conductive electrode 75
Were fabricated on the same glass substrate 51. Obtained TFT
Has electrical characteristics of PTFT and a mobility of 20 (cm ² / Vs),
Vth is -5.9 (V), and the mobility is 40 (cm) in NTFT.
² / Vs) and Vth was 5.0 (V).

One substrate for a liquid crystal device was manufactured according to the method described above. The arrangement of the electrodes and the like of this liquid crystal display device is shown in FIG. The NTFT 76 and PTFT 77 are provided at the intersection of the first signal line 40 and the second signal line 41. A matrix configuration using such a C / TFT is provided. The NTFT 76 is connected to the second signal line 41 via the lead 71 at the input end of the drain 63, and is connected to the gate 5.
Reference numeral 6 is connected to a signal line 40 on which a multilayer wiring is formed. The output terminal of the source 62 is connected to a pixel electrode 75 via a contact 72.

On the other hand, the PTFT 77 has the input terminal of the drain 60 connected to the second signal line 41 via the lead 73,
The gate 58 is connected to the signal line 40, and the output terminal of the source 59 is connected to the pixel electrode 75 via the contact 72 in the same manner as the NTFT. The present embodiment is configured by repeating such a structure left, right, up and down.

Next, as a second substrate, an ITO (indium tin oxide film) was formed by a sputtering method on a substrate in which a silicon oxide film was laminated by 2000 mm on a soda lime glass by a sputtering method. This ITO is between room temperature and 150
The film was formed at 200 ° C. and achieved by oxygen at 200 to 400 ° C. or annealing in the air. In addition, a color filter was formed on this substrate to form a second substrate. Thereafter, a polyamic acid is applied on the first substrate and the second substrate by an offset printing method, and heated at 250 ° C. for 3 hours to obtain a polyimide film as a liquid crystal alignment film. After rubbing was performed using a cotton cloth, seal printing was performed using a screen printing method.

Then, SiO ₂ particles having a diameter of 2.8 μm were scattered as spacers on the TFT production substrate, and bonded to a seal-printed substrate. At this time, the rubbing directions of the two substrates are set to be parallel. The distance between the substrates was measured at five points by an interference cell thickness gauge and found to be 2.7 to 2.8 microns. After the injection of the liquid crystal, observation using a polarizing microscope revealed that the liquid crystal molecules were substantially aligned in the rubbing direction over the entire liquid crystal layer. Then, a polarizing plate was attached to the liquid crystal cell so as to form crossed Nicols. At this time,
The polarization axis of the polarizing plate on which light is incident is 45
°. Then, by applying a voltage to the TFT element, the response speed of the liquid crystal was observed using an oscilloscope. The drain voltage used at this time is 5V to 20V.
V, frequency is 75 Hz. The liquid crystal used was ZLI-4
792 (Merck) and the alignment film is LP (Toray)
It is. As a result, a response speed of 10 ms to 50 microseconds was obtained. This is about 10 times to about 1000 times faster in rising speed than the conventional TN type liquid crystal electro-optical device, and almost corresponds to the response time of the ferroelectric liquid crystal. Then, a liquid crystal driver was connected by the COG method. Thus, a transmission type liquid crystal display device was obtained. In this embodiment, the complementary T
Although the case of FT is shown, only N-type or only P-type may be used.

[Embodiment 2] In Embodiment 1, the case where a transmission type panel is manufactured has been described. In this embodiment, a reflection type panel will be described. In this case, two polarizing plates may be used in the same manner as in the transmission type, but display can be performed with only one polarizing plate, and a bright screen can be obtained as compared with a normal reflection type display. After an ITO electrode was formed on the substrate on which the TFT was formed in the same manner as in Example 1, the electrode forming surface of the two substrates was also changed to Example 1
A polyimide thin film was obtained in the same manner as described above. Then, a rubbing treatment was performed on the polyimide production surface of one of the substrates using a cotton cloth. 1.4 micron SiO ₂ particles were sprayed as spacers. After measuring the distance between the sealed substrate and the cell bonded to the counter substrate by a known interference method, a nematic liquid crystal was injected by a vacuum injection method. The distance between the substrates was measured at five places and found to be 1.3 to 1.4 microns.

After sealing the liquid crystal injection port, a polarizing plate was attached to the front surface of the panel, and a reflector was attached to the back surface. At this time, the angle of the polarizing axis of the polarizing plate was 45 ° with respect to the rubbing axis.
Angle. Thus, the circuit for driving the liquid crystal was connected, and the reflection type liquid crystal panel was completed.

Embodiment 3 In this embodiment, a case where the present invention is applied to a color projector will be described with reference to FIG. Since the color filter is not used in the projector according to the present embodiment, a bright projector having higher transmittance than that of the conventional projector can be manufactured.

In FIG. 5, a wavelength 63 is used as the red light source 81.
He-Ne laser having a peak around 3 nm, Ar laser having a peak around 515 nm as a green light source 82, and Ar laser having a peak around 477 nm as a blue light source 83 are used to emit these laser beams. The optical system 84 processes the outer shape and light density to necessary light conditions, and the liquid crystal panels 85 and 8 manufactured in the first embodiment.
Irradiate 6,87 (excluding color filters). The light that has passed through the liquid crystal panel is combined by an optical system 88 whose transmission light amount is limited as ON, OFF, or gray scale by a shutter function of the liquid crystal panel, and is further enlarged and displayed on a display screen 89.

In this embodiment, since the light source has a single wavelength, the optical conditions when passing through the liquid crystal panel can be adjusted in each liquid crystal panel. Sharp display can be performed without blurring of the screen. As the laser light used in this embodiment, in addition to the above-described gas laser, a laser light using a metal vapor of cadmium or zinc, a solid-state laser using ruby or the like, or a laser light of any other type has a peak wavelength in the visible light region. Can be used. In addition, it is also possible to use a device that can emit light in the visible light region by passing through a special optical system at a wavelength other than the normal emission wavelength, such as a second harmonic of a YAG laser.

Normally, three laser beams having emission wavelengths close to the red, blue, and green wavelengths are used. However, colors are synthesized by using four or more laser beams having different wavelengths to form a color. Display can also be performed.

[0054]

As described above, the present invention is capable of performing display in a new mode which has not been provided in the conventional liquid crystal electro-optical device at all. A liquid crystal electro-optical device which is easy and has a very high response speed can be obtained. Further, according to the present invention, a large-screen display can be easily obtained. Therefore, the present invention can be expected to be applied to many fields such as a large-screen liquid crystal display.

[Brief description of the drawings]

FIG. 1 shows a basic structure of a TFT that can be used in the present invention.

FIG. 2 shows a circuit diagram of an embodiment.

FIG. 3 shows an arrangement of active elements in the embodiment.

FIG. 4 shows a cross-sectional view of a manufacturing process of a TFT in an example.

FIG. 5 shows a basic configuration of a color projector in the embodiment.

[Explanation of symbols]

 15, 66 Gate electrode 28 Channel length 25, 51 Substrate 81, 82, 83 Laser light 84, 88 Optical system 85, 86, 87 Liquid crystal panel 89 Display screen

Claims (5)

(57) [Claims] 1. A liquid crystal electro-optical device for performing display using refractive index anisotropy without twisting a nematic liquid crystal material provided between a pair of substrates, wherein one of the pair of substrates is provided. , the provided thin film transistors connected to the pixel electrode, the thin film transistor has a source region formed in said one of the substrate, the drain region and silicon having crystallinity including a channel formation region sandwiched between the regions a semiconductor layer formed of film, said over the channel formation region is formed via a gate insulating film upper surface and the side surface is covered with the anodic oxide barrier type, and a gate electrode made of a metal, the source region And the drain region comprises the anodic oxide.
A liquid crystal electro-optical device , wherein an impurity is introduced as a mask . 2. The liquid crystal electro-optical device according to claim 1, wherein the metal is aluminum or tantalum . 3. The liquid crystal material according to claim 1 , wherein the liquid crystal material has a positive dielectric constant anisotropy, and a liquid crystal molecule in the liquid crystal material has a molecular long axis with respect to the substrate surface. A liquid crystal electro-optical device characterized by being aligned so as to be parallel. 4. The liquid crystal electro-optical device according to claim 1 , wherein the liquid crystal electro-optical device is of a reflection type in which a polarizing plate is disposed only on a light incident surface side. 5. The liquid crystal electro-optical device according to claim 1 , wherein the device is used for a projector.